In recent years, in accordance with reduction in size and weight of a mobile electronic device, also in a lithium-ion battery and a lithium-polymer battery for use in such a mobile electronic device, the reduction in weight has been attained by using, in place of a conventional metallic can, a laminated external packaging material in which plastic films are adhered to both surfaces of an aluminum foil having a thickness of about 20 to 100 μm as an external packaging material.
In this laminated external packaging material, however, a soft aluminum foil softened by annealing is used so that press forming thereof can be performed. Therefore, there are such drawbacks that the packaging material deteriorates in material strength, resulting in easy breakage due to external impacts and that pinholes can be easily generated in the packaging material. To cope with the problems, in a laminate battery using a conventional laminated external packaging material, the battery is often put in a plastic injection molded container to compensate for the deteriorated strength of the external packaging material (see Patent Document 1). This results in an increased weight and an increased number of components per battery.
Under the circumstances, recently proposed is a method for reinforcing a battery main body by wrapping around the main body with a non-annealed hard aluminum foil or a non-annealed hard aluminum foil having a plastic film adhered on one or both surfaces of the foil and fitting plastic components into both end portions of the battery main body.    Patent Document 1: Japanese Unexamined Laid-open Publication No. H11-185728